Panels applied to the rear of a frame to retain the picture and protective panel are already known, as well as retaining them to the frame by means of metal elements in various shapes and forms. The traditional panels render the construction of a frame somewhat complex, as they must be shaped so that the above-mentioned retaining elements can be applied to them.
A further problem of these panels derives from the fact that the replacement of the picture may only be carried out by removing and then re-applying the metal elements in question, which is not always easy to do.
Another notable problem derives from the fact that in the case of excessive wear and tear or breakage of only one of the metal retaining elements, finding an identical element is often difficult, if not impossible, making the frame virtually useless.
A further problem which must not be overlooked consists in the fact that, in general, the retaining elements of the panel have parts which are to be attached to the frame and parts which are fixed to panel behind the picture, by which the metal element is hooked and which also protect the picture from pressure, traction or other stresses generated by the retaining hook. Besides rendering the frame more costly, because there is a supplementary component, i.e. the protective panel, this makes larger size frames much heavier.
A panel in accordance with the present invention is applied to the rear of the frame for retaining the picture and its protective panel, eliminating all the problems mentioned above.
One of the principle objects of the present invention is therefore to provide a panel of the type mentioned above which completely eliminates every type of metal retaining element, with the consequent advantages.
Another object of the invention is to provide a panel the removal and re-application of which after having substituted the picture is extremely easy and rapid.